Measure and fix how fast a site loads and responds on a mid-range phone - LCP, CLS, total blocking time, bytes by type, oversized images, font weight - with a Playwright script that throttles CPU and network, then fix the causes in order of impact and re-measure. Covers animated canvases and WebGL backgrounds, which must pause offscreen and fall back on weak devices. Use before launch, when a page feels slow on a phone, or after adding heavy visuals.
